The invention relates to a fastener. The invention is specifically related to a self-attaching double or single ended stud.
Studs are used by the automotive industry to assemble vehicles in which many components of various kinds are attached to metal plates or panels. For example studs are used to attach lamps, brackets, modules, and sheet metal parts to the vehicle. When such parts are attached a nut is placed over the end of the installed stud and the nut is tightened with rotating tools such as an air or electric torque gun, set to the specified torque values. The self-attaching stud must therefore have the necessary and sufficient anti-torque or rotation resistance (the force that keeps the stud from rotating on the mating metal plate when the nut is tightened on the stud).
When self-attaching studs are being driven into a metal panel the studs may be continuously supplied to the installation tooling through an outlet of a supply device, such as a hopper. Studs are easily adapted to automatic feeding machines because of the large length to diameter ratio. The larger the ratio the more efficient the high-speed feeding operations become.
After a component is attached to the stud on the metal plate, external forces such as vibration and shear and tensile forces are applied to the joint (the stud and nut combination with the attached part). These forces act upon the stud from the pull through direction attempting to pull the studs from the metal plate in which they are attached. Therefore, the installed stud must have sufficient push out and pull out resistance. Previously, the only way to ensure a very high push out or pull out force was to weld the stud to the mating material. Earlier attempts to use double-ended studs that were not welded resulted in studs with very low push-in and push-out values. A low push-out value limits the number of applications in which the stud can be used, since a stud with a low push-out value can not attach parts of any significant amount of mass.
Thus, there is a need in the industry for a stud that can be attached by means other than welding where the stud also has a very high push-out force, and where the stud can be configured as either a single-ended stud or a doubleended stud.
One aspect of the present invention is a self-forging stud for installation in a host panel and for fastening a component to the host panel, which includes at least one shaft, having a longitudinal axis. An annular flange extends radially from the shaft at a substantially right angle with respect to the longitudinal axis. A shoulder for engagement with the host panel has a top adjacent to the shaft and a base adjacent to the flange. The shoulder extends radially from the shaft wherein the shoulder and the flange define an undercut therebetween at the base of the shoulder such that a diameter of the shoulder is smaller at the base than at the top. A forging collar has a central aperture and is received in sleeve-like fashion over the shaft and is retained therewith. The forging collar includes a forging surface at an end most proximate to the annular flange wherein the forging surface is in deformable contact with the top of the shoulder. The forging collar further includes a first forging ring extending from the forging collar end and toward the annular flange for forging the host panel into engagement with the undercut.
Another aspect of the present invention is a self-forging stud for installation in a host panel and for fastening a component to the host panel wherein the self-forging stud includes a shaft having a longitudinal axis and a first and a second end. An annular flange coaxial to the shaft is positioned intermediate between the first and second ends of the shaft. A shoulder is positioned adjacent to a surface of the flange and is coaxial thereto wherein the shoulder has an outer peripheral face. The peripheral shoulder face and the flange surface define an acute angle therebetween. A forging collar has a central aperture and is received in sleeve-like fashion over the shaft and is retained thereto. The forging collar includes a forging surface at an end most proximate to the annular flange and is in deformable contact with the top of the shoulder. A first forging ring extends from the end of the forging collar and toward the annular flange for forging the host panel into engagement with the acute angle.
Yet another aspect of the present invention is a method for installing a self-forging stud in a host panel aperture wherein the stud has an annular flange with anti-rotation tabs and further has a shoulder with a crown and a shoulder face with a back-angled undercut wherein the shoulder is received in an aperture in the panel. The method for installation comprises the steps of supporting one end of the stud and the stud flange with an installation fixture and then placing a cylindrical forging collar over an opposite end of the stud wherein an end of the forging collar has a forging surface bearing on the shoulder crown and a forging ring extending from the forging collar end and bearing on the panel area proximate to the panel aperture receiving the stud. Next, a force is applied to the forging collar in a direction toward the installation fixture and thereby deforming the panel material into the back angled undercut with the forging collar forging ring and deflecting the shoulder crown radially outward with the bearing surface of the forging collar to engage the panel at the periphery of the panel aperture.
These and other advantages of the invention will be further understood and appreciated by those skilled in the art by reference to the following written specification, claims and appended drawings.